采用光纤激光变极性TIG复合填丝焊接4 mm厚的A7N01铝合金，研究了焊接电流、焊接速度对焊缝成形及气孔的影响规律，同时分析了优化工艺参数条件下焊接接头的显微组织和力学性能。结果表明，随着焊接电流的增加，焊缝正面熔宽增加，背面熔宽基本不变；而焊接速度降低，焊缝正面和背面熔宽均增加，焊缝内部气孔减少；且在激光功率为6 kW、焊接电流为180 A、焊接速度为4 m/min、送丝速度为4 m/min时，获得成形良好内部无缺陷的焊接接头；焊缝横截面呈典型的上宽下窄的特征，从熔合线至焊缝中心，焊缝显微组织依次为细小等轴晶、柱状晶、等轴树枝晶形态，且焊缝中心的等轴树枝晶晶粒尺寸自上而下逐渐减小，二次枝晶逐渐弱化；焊缝区的硬度值低于母材，存在接头软化现象，其接头抗拉强度均值为369.8 MPa，约为母材的83%，延伸率约为4.0%，拉伸断裂于焊缝区，拉伸断口呈典型的韧性断裂特征。

A7N01 aluminum alloy with the thickness of 4 mm is welded by using fiber laser-variable polarity TIG hybrid welding with filler wire. The effects of both welding current and welding speed on weld formation and porisities are discussed. The microstructure and mechanical properties of the joint obtained at optimal welding parameters are investigated. Experimental results show that the top weld width increases and the bottom weld width is unchanged with the increase of the welding current. With the welding speed decreasing, both the top and the bottom width increase, and the internal porosities decreases. Under the condition of laser power of 6 kW, welding current of 180 A, welding speed of 4 m/min and wire feeding rate of 4 m/min, the joint with good formation and few welding defects is obtained. Weld cross section is characterized by the wide top weld width and narrow bottom weld width. The microstructure of the joint is composed of equiaxed grain zone, columnar zone and equiaxed dendrite zone from the fusion line to the center of weld. The sizes of the grains and equiaxed dendrites from the top to the bottom are gradually reduced along the weld centerline. The fusion zone hardness is lower than that of the base metal, which indicates that the soften zone is occurred in the joint. The average tensile strength of joints is 369.8 MPa, which is approximately 83% of the base metal. And the extension rate is about 4%. The tensile fracture occurs in the weld zone, and the fracture morphology is distinctly ductile characteristics.